Heat treating is a big deal. It demands advanced technology, specialized capital equipment, and the skill that only experienced system operators can provide.
For all these reasons, the manufacturers that require heat treating to make their products better, or qualified, frequently rely on off-site suppliers for the heat-treating services they need. These may include producers of specialty metal bar products, castings, or forgings to be used in aircraft construction, oil-and-gas processing, or power-generation systems.
Perhaps forgings are the best example. The expanding variety of specially designed forgings in lightweight but hard materials is amplifying the importance of heat treating to achieve mechanical qualities that the parts’ designers intended. This situation underscores how forgers rely on heat treating specialists to fulfill their own manufacturing potential.
The vacuum heat treating furnace installed in 2016 by Solar Atmospheres of Western Pennsylvania is a reminder that heat treating is a big deal. The furnace stretches 48 ft. long and spans 6.5 ft. in diameter and it’s capable of treating 150,000lb. loads. It performs annealing, stress-relieving, aging, degassing, and brazing under vacuum, and it’s the largest commercial vacuum furnace, according to Matt Knauff, customer service manager.
Solar Atmospheres has three other commercial heat-treating centers located in Souderton, PA, Greenville, SC, and Fontana, CA. Each location has different systems and capabilities. An affiliated company, Solar Manufacturing, designed the 48-ft furnace, and both organizations are led by CEO William R. Jones, a pioneer in the field of vacuum furnace technology.
The plant in Hermitage, PA is about 60 miles north of Pittsburgh and it has 14 other vacuum furnaces and five air furnaces installed. They include three 24-ft vacuum furnaces, a 36-ft vacuum furnace, and a 20-ft air furnace installed this year, with a maximum operating temperature of 1,450°F (+10°F) and a 40,000-lb. load capacity.
The plant also has advanced capabilities for 20-bar quenching and cryogenic treatment.
However, it is the 48-ft. model that is the big deal, drawing interest on YouTube and elsewhere. Its scale and capabilities offer a statement about Solar Atmospheres’ expertise in heat-treating processes. With a 2,400°F maximum operating temperature, +10°F uniformity, and rapid vacuum pump down to 10-6 Torr, it also represents the state-of-technology for industrial thermal processing. And, by scaling up the potentiality for heat-treating parts, the new furnace incentivizes forgers and other potential customers to consider what new projects or programs they might undertake.
What is vacuum treatment? — "Vacuum heat treatment is the process of heat treating in a totally inert atmosphere,” Knauff explaned. A vacuum furnace is a sealed chamber with a system capable of pumping the furnace atmosphere to very low vacuum levels.
“The absence of oxygen in the chamber prevents oxidation and discoloration,” Knauff continued. “Unlike most heat-treatment processes that expose metals to open air or other reducing atmospheres while at elevated temperatures, vacuum processing is oxygen-free.” This point is critical to understanding the scope of applications for the 48-ft. furnace, involving hard and lightweight materials that are also reactive – making normal heat-treating impossible.
Solar Atmospheres’ customers are manufacturers of parts used in aerospace, medical, defense, automotive and power-generation markets. They range from high-profile OEMs to local machine shops.
The 48-ft vacuum furnace was built to meet the needs of all these customers. For example, a customer producing long Inconel tubes for use in nuclear-power system needed those products heat-treated, but at a low vacuum level, of course. “As we designed and built the furnace, more and more customers started to find ways to utilize the furnace capacity,” Knauff recalled.
The vacuum furnace is a horizontal arrangment with internal quenching capability. It has two, 48-foot load cars, each capable of handling 150,000-lb loads. The water cooled chamber consists of an outer carbon steel wall and an inner wall that is made of 300 Series stainless steel. It has a graphite-lined hot zone capable of 2400°F operating temperatures, with +10°F uniformity.
The hot zone is powered by eight power supplies: Each power supply can be individually controlled for “pinpoint temperature uniformity,” according to Knauff.
The furnace has three diffusion pumps capable of pumping down to less than 10-6 Torr, and the rapid-quench function is capable of 2-bar quenching. The quench is powered by three 300-hp blower motors.
Operators control the vacuum heat-treating process through a SolarVac touchscreen monitor via a Wonderware program for process recipes. The furnace provides “instantaneous response” to the PLC, Knauff noted.
"We commissioned the furnace in September 2016 to a limited amount of production," he explained. “It is currently fully operational and running production 24/7."
Manufacturers have taken note of the new furnace, to be sure. The ability to offer vacuum heat-treating for oversized parts is unavailable anywhere else in the U.S., and manufacturers (including forgers) are quoting new projects because of the availability of such a process. “Our customers are seeing a cost savings by running much larger orders, compared to processing multiple runs in a smaller furnace,” Knauff indicated.
Advantage, forgers — The advantages are fairly apparent to forgers. The size of their parts presents no limit to effective vacuum heat-treament with no oxidation, dimensional control, and degassing as further benefits.
“The size of the furnace allows companies to produce larger forgings,” he emphasized. “Because there is no oxidation of the metal, there is no need to grind or blast the surface after heat treating, which saves time and money for our customers.”
In addition, Solar Atmospheres’ patented dual load-car system and the use of graphite in the furnace makes it possible for engineers to minimize part distortion during the heat-treating process, “even creep-form into shape,” Knauff noted.
“This furnace is perfect for degassing large titanium forgings,” he added. “We currently process a number of large forging projects for customers that involve titanium degassing, annealing, and stress relieving.”
The 48-ft. furnace represented a capital investment over $10 million, including a new 18,000-sq.ft. expansion. Earlier this year, Solar Atmospheres of Western Pennsylvania added a 10,000-sq.ft. tensile testing operation adjacent to the heat-treating operation, and a new 20-ft. air furnace to help address growing demand for air aging processes. “We are constantly asking for and listening to customer feedback,” Knauff said, suggesting that in the heat-treatment business, customer service is a big deal, too.